There exist in the patent literature a variety of patents which deal with monitoring the opening and closing of a door. The following U.S. patents are representative of the prior art: 3,816,745; 3,875,403; 3,987,428; 4,266,124; 4,319,332; 4,324,977; 4,390,867; 4,583,082; 4,650,990; 4,742,337; 4,812,810; 4,841,283; 4,903,009; 4,965,551; 5,015,840; 5,063,288; 5,111,184; 5,134,386 and 5,138,299.
The most relevant prior art known to applicants is U.S. Pat. No. 5,219,386 to Kletzmaier et al which describes a locker unit comprising a plurality of lockers. Each locker is provided with a mechanical lock and an auxiliary lock having an electric drive. Unlike the present invention, Kletzmaier et al does not show or suggest communications apparatus for monitoring the open/closed status of the plurality of the lockers via plural alternative serial communications pathways.